The present invention relates to a thermoformed container which is excellent in heat-resistance, oil-resistance, chemical stability under high temperature and high humidity and low gas permeability and is obtained by thermoforming a poly(arylene sulfide) (hereinafter referred to as "PAS") and a process for producing the container.
PAS is, as has been publicly known, an excellent engineering plastic having thermal resistance, chemical resistance (acid-resistance, alkali-resistance and solvent-resistance), oil-resistance, hot water-resistance, processability and mechanical properties and is used in various fields.
Further, taking advantage of these excellent properties, its use is being extended to the fields of fibers and films.
On the other hand, in recent years, as a heat-resistant plastic container, for instance, a thermoformed container for foodstuff which can be used in an electronic range and an electric oven for domestic use and resist to an oven temperature of almost 200.degree. C., an easily crystallizable polyethylene terephthalate (hereinafter referred to as "PET") has attracted public attention.
However, the PET container has a defect that it can not resist to a temperature of higher than 200.degree. C., particularly higher than 220.degree. C. in an electric oven. As is well known, PAS has higher melting point than PET and from a viewpoint of heat-resistance, PAS has more excellent performance than PET. Further, PAS has more excellent chemical stability under high temperature and high humidity and solvent-resistance than PET.
These excellent properties of PAS are mainly due to the fact that PAS is crystallized.
The present invention relates to obtaining a heat-resistant container by thermoforming a sheet of PAS which is substantially amorphous.
As a result of the present inventors' extensive studies to obtain a heat-resistant PAS container by thermoforming taking advantage of these characteristic points of PAS, the present inventors have attained the present invention.